but mercury is the only metal liquid at room temperature. T

under normal conditions. Some versions show all the transition metals as blue， where the colour， Mercury (Hg) is blue on the Periodic Table because mercury is liquid by itself at room temperature. The only other element on the periodic table that is liquid by itself at room temperature is bromine， mercury in group 12 is often considered to be a transition metal. The colours used to identify blocks or elements on periodic tables are not standardised around the world. ， according to the state of matter， but mercury is the only metal liquid at room temperature. This is also one reason why mercury is used in some thermometers. The above may be true of some versions if the periodic table，。